Porous composite particles and cosmetic compositions comprising the same

Abstract

Disclosed are porous composite particles and compositions comprising the same. The porous composite particles comprising base of an amphiphilic or hydrophobic polymer and 0.1 to 20% of a pigment based on the total weight of porous composite particles, where said particles have 50 to 95 vol % internal porosity and an outer surface which is either continuous and devoid of pores or is discontinuous comprising plurality of pores whose total area is 0.01 to 30% of the total outer surface area. When typically applied, the compositions impart improving the characteristics of skin.

1 . Porous composite particles comprising base of an amphiphilic or hydrophobic polymer and 0.1 to 20% of a pigment based on the total weight of porous composite particles, where said particles have 50 to 95 vol % internal porosity and an outer surface which is either continuous and devoid of pores or is discontinuous comprising plurality of pores whose total area is 0.01 to 30% of the total outer surface area wherein said composite particles comprise a combination of pigments comprising a white pigment and non-white pigment;
 wherein said porous composite particles are prepared by a process comprising the steps of:
 (i) forming a w/o emulsion comprising a water phase and an oil phase, said oil phase comprising said polymer, an organic solvent for solubilizing the polymer and said pigment; 
 (ii) further emulsifying said w/o emulsion in an outer water phase comprising an emulsifier to form a w/o/w double emulsion; 
 (iii) mixing said w/o/w double emulsion with additional water to allow said solvent to diffuse into said additional water to precipitate said porous composite particles. 
   
     
     
         2 . Porous composite particles as claimed in  claim 1  wherein said total area is 0.1 to 10% of said total outer surface area. 
     
     
         3 . Porous composite particles as claimed in  claim 1  wherein said porous composite particles are spherical or spheroidal. 
     
     
         4 . Porous composite particles as claimed in  claim 3  wherein diameter of said porous composite particles is 0.5 to 100 microns. 
     
     
         5 . Porous composite particles as claimed in  claim 1  wherein said internal porosity is due to plurality of disconnected air pockets. 
     
     
         6 . Porous composite particles as claimed in  claim 1  wherein said internal porosity is due to plurality of interconnected air pockets. 
     
     
         7 . Porous composite particles as claimed in  claim 1  wherein particle size of said pigment is 0.01 to 5 microns. 
     
     
         8 . Porous composite particles as claimed in  claim 1  wherein said pigment is inorganic. 
     
     
         9 . Porous composite particles as claimed in  claim 8  wherein said pigment is iron oxide, titanium dioxide, zinc oxide, zirconium oxide or a mixture thereof. 
     
     
         10 . (canceled) 
     
     
         11 . Porous composite particles as claimed in  claim 1  wherein said amphiphilic polymer is selected from methoxy polyethylene glycol polylactic acid copolymer, polyoxyethylene and polyoxypropylene copolymer, polystyrene and polyethylene glycol copolymer, polystyrene and polyacrylate copolymer, polystyrene and polyacrylate hydroxyethyl ester copolymer, polymethyl methacrylate and polyacrylate copolymer, polymethyl methacrylate and polyacrylate hydroxyethyl ester copolymer, methyl methacrylate and methacrylate copolymer, methyl methacrylate, β-hydroxyethyl methacrylate copolymer or mixture thereof. 
     
     
         12 . Porous composite particles as claimed in  claim 1  wherein said hydrophobic polymer is selected from polystyrene, polychloromethylstyrene, polyglycidyl methacrylate or a mixture thereof. 
     
     
         13 . (canceled) 
     
     
         14 . A cosmetic composition comprising porous composite particles as claimed in  claim 1  in a cosmetically acceptable carrier. 
     
     
         15 . A method of improving the characteristics of skin comprising a step of topically applying to skin the cosmetic composition as claimed in  claim 14 .